drivers/base/driver.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * driver.c - centralized device driver management
   4  *
   5  * Copyright (c) 2002-3 Patrick Mochel
   6  * Copyright (c) 2002-3 Open Source Development Labs
   7  * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
   8  * Copyright (c) 2007 Novell Inc.
   9  */
  10
  11 #include <linux/device/driver.h>
  12 #include <linux/device.h>
  13 #include <linux/module.h>
  14 #include <linux/errno.h>
  15 #include <linux/slab.h>
  16 #include <linux/string.h>
  17 #include <linux/sysfs.h>
  18 #include "base.h"
  19
  20 static struct device *next_device(struct klist_iter *i)
  21 {
  22         struct klist_node *n = klist_next(i);
  23         struct device *dev = NULL;
  24         struct device_private *dev_prv;
  25
  26         if (n) {
  27                 dev_prv = to_device_private_driver(n);
  28                 dev = dev_prv->device;
  29         }
  30         return dev;
  31 }
  32
  33 /**
  34  * driver_set_override() - Helper to set or clear driver override.
  35  * @dev: Device to change
  36  * @override: Address of string to change (e.g. &device->driver_override);
  37  *            The contents will be freed and hold newly allocated override.
  38  * @s: NUL-terminated string, new driver name to force a match, pass empty
  39  *     string to clear it ("" or "\n", where the latter is only for sysfs
  40  *     interface).
  41  * @len: length of @s
  42  *
  43  * Helper to set or clear driver override in a device, intended for the cases
  44  * when the driver_override field is allocated by driver/bus code.
  45  *
  46  * Returns: 0 on success or a negative error code on failure.
  47  */
  48 int driver_set_override(struct device *dev, const char **override,
  49                         const char *s, size_t len)
  50 {
  51         const char *new, *old;
  52         char *cp;
  53
  54         if (!override || !s)
  55                 return -EINVAL;
  56
  57         /*
  58          * The stored value will be used in sysfs show callback (sysfs_emit()),
  59          * which has a length limit of PAGE_SIZE and adds a trailing newline.
  60          * Thus we can store one character less to avoid truncation during sysfs
  61          * show.
  62          */
  63         if (len >= (PAGE_SIZE - 1))
  64                 return -EINVAL;
  65
  66         /*
  67          * Compute the real length of the string in case userspace sends us a
  68          * bunch of \0 characters like python likes to do.
  69          */
  70         len = strlen(s);
  71
  72         if (!len) {
  73                 /* Empty string passed - clear override */
  74                 device_lock(dev);
  75                 old = *override;
  76                 *override = NULL;
  77                 device_unlock(dev);
  78                 kfree(old);
  79
  80                 return 0;
  81         }
  82
  83         cp = strnchr(s, len, '\n');
  84         if (cp)
  85                 len = cp - s;
  86
  87         new = kstrndup(s, len, GFP_KERNEL);
  88         if (!new)
  89                 return -ENOMEM;
  90
  91         device_lock(dev);
  92         old = *override;
  93         if (cp != s) {
  94                 *override = new;
  95         } else {
  96                 /* "\n" passed - clear override */
  97                 kfree(new);
  98                 *override = NULL;
  99         }
 100         device_unlock(dev);
 101
 102         kfree(old);
 103
 104         return 0;
 105 }
 106 EXPORT_SYMBOL_GPL(driver_set_override);
 107
 108 /**
 109  * driver_for_each_device - Iterator for devices bound to a driver.
 110  * @drv: Driver we're iterating.
 111  * @start: Device to begin with
 112  * @data: Data to pass to the callback.
 113  * @fn: Function to call for each device.
 114  *
 115  * Iterate over the @drv's list of devices calling @fn for each one.
 116  */
 117 int driver_for_each_device(struct device_driver *drv, struct device *start,
 118                            void *data, int (*fn)(struct device *, void *))
 119 {
 120         struct klist_iter i;
 121         struct device *dev;
 122         int error = 0;
 123
 124         if (!drv)
 125                 return -EINVAL;
 126
 127         klist_iter_init_node(&drv->p->klist_devices, &i,
 128                              start ? &start->p->knode_driver : NULL);
 129         while (!error && (dev = next_device(&i)))
 130                 error = fn(dev, data);
 131         klist_iter_exit(&i);
 132         return error;
 133 }
 134 EXPORT_SYMBOL_GPL(driver_for_each_device);
 135
 136 /**
 137  * driver_find_device - device iterator for locating a particular device.
 138  * @drv: The device's driver
 139  * @start: Device to begin with
 140  * @data: Data to pass to match function
 141  * @match: Callback function to check device
 142  *
 143  * This is similar to the driver_for_each_device() function above, but
 144  * it returns a reference to a device that is 'found' for later use, as
 145  * determined by the @match callback.
 146  *
 147  * The callback should return 0 if the device doesn't match and non-zero
 148  * if it does.  If the callback returns non-zero, this function will
 149  * return to the caller and not iterate over any more devices.
 150  */
 151 struct device *driver_find_device(const struct device_driver *drv,
 152                                   struct device *start, const void *data,
 153                                   device_match_t match)
 154 {
 155         struct klist_iter i;
 156         struct device *dev;
 157
 158         if (!drv || !drv->p)
 159                 return NULL;
 160
 161         klist_iter_init_node(&drv->p->klist_devices, &i,
 162                              (start ? &start->p->knode_driver : NULL));
 163         while ((dev = next_device(&i)))
 164                 if (match(dev, data) && get_device(dev))
 165                         break;
 166         klist_iter_exit(&i);
 167         return dev;
 168 }
 169 EXPORT_SYMBOL_GPL(driver_find_device);
 170
 171 /**
 172  * driver_create_file - create sysfs file for driver.
 173  * @drv: driver.
 174  * @attr: driver attribute descriptor.
 175  */
 176 int driver_create_file(const struct device_driver *drv,
 177                        const struct driver_attribute *attr)
 178 {
 179         int error;
 180
 181         if (drv)
 182                 error = sysfs_create_file(&drv->p->kobj, &attr->attr);
 183         else
 184                 error = -EINVAL;
 185         return error;
 186 }
 187 EXPORT_SYMBOL_GPL(driver_create_file);
 188
 189 /**
 190  * driver_remove_file - remove sysfs file for driver.
 191  * @drv: driver.
 192  * @attr: driver attribute descriptor.
 193  */
 194 void driver_remove_file(const struct device_driver *drv,
 195                         const struct driver_attribute *attr)
 196 {
 197         if (drv)
 198                 sysfs_remove_file(&drv->p->kobj, &attr->attr);
 199 }
 200 EXPORT_SYMBOL_GPL(driver_remove_file);
 201
 202 int driver_add_groups(const struct device_driver *drv,
 203                       const struct attribute_group **groups)
 204 {
 205         return sysfs_create_groups(&drv->p->kobj, groups);
 206 }
 207
 208 void driver_remove_groups(const struct device_driver *drv,
 209                           const struct attribute_group **groups)
 210 {
 211         sysfs_remove_groups(&drv->p->kobj, groups);
 212 }
 213
 214 /**
 215  * driver_register - register driver with bus
 216  * @drv: driver to register
 217  *
 218  * We pass off most of the work to the bus_add_driver() call,
 219  * since most of the things we have to do deal with the bus
 220  * structures.
 221  */
 222 int driver_register(struct device_driver *drv)
 223 {
 224         int ret;
 225         struct device_driver *other;
 226
 227         if (!bus_is_registered(drv->bus)) {
 228                 pr_err("Driver '%s' was unable to register with bus_type '%s' because the bus was not initialized.\n",
 229                            drv->name, drv->bus->name);
 230                 return -EINVAL;
 231         }
 232
 233         if ((drv->bus->probe && drv->probe) ||
 234             (drv->bus->remove && drv->remove) ||
 235             (drv->bus->shutdown && drv->shutdown))
 236                 pr_warn("Driver '%s' needs updating - please use "
 237                         "bus_type methods\n", drv->name);
 238
 239         other = driver_find(drv->name, drv->bus);
 240         if (other) {
 241                 pr_err("Error: Driver '%s' is already registered, "
 242                         "aborting...\n", drv->name);
 243                 return -EBUSY;
 244         }
 245
 246         ret = bus_add_driver(drv);
 247         if (ret)
 248                 return ret;
 249         ret = driver_add_groups(drv, drv->groups);
 250         if (ret) {
 251                 bus_remove_driver(drv);
 252                 return ret;
 253         }
 254         kobject_uevent(&drv->p->kobj, KOBJ_ADD);
 255         deferred_probe_extend_timeout();
 256
 257         return ret;
 258 }
 259 EXPORT_SYMBOL_GPL(driver_register);
 260
 261 /**
 262  * driver_unregister - remove driver from system.
 263  * @drv: driver.
 264  *
 265  * Again, we pass off most of the work to the bus-level call.
 266  */
 267 void driver_unregister(struct device_driver *drv)
 268 {
 269         if (!drv || !drv->p) {
 270                 WARN(1, "Unexpected driver unregister!\n");
 271                 return;
 272         }
 273         driver_remove_groups(drv, drv->groups);
 274         bus_remove_driver(drv);
 275 }
 276 EXPORT_SYMBOL_GPL(driver_unregister);